Medium Voltage Cables/Rating Factors for thermal resistivity/Cables laid direct in Ground


Cables laid direct in Ground

Rating Factors for variation in Thermal resistivity of Soil (Average Values)


Size of cables
sqmm
Soil thermal resistivity in K.m/W
  0.8 0.9 1.0 1.5 2.0 2.5 3.0
Single core              
50 1.15 1.11 1.07 0.91 0.81 0.73 0.68
70 1.16 1.12 1.07 0.91 0.81 0.73 0.68
95 1.16 1.12 1.07 0.91 0.81 0.73 0.68
120 1.16 1.12 1.07 0.91 0.81 0.73 0.68
150 1.17 1.12 1.07 0.91 0.81 0.73 0.68
185 1.17 1.12 1.07 0.91 0.81 0.73 0.68
240 1.17 1.12 1.07 0.91 0.80 0.73 0.68
300 1.18 1.12 1.07 0.91 0.80 0.73 0.68
400 1.18 1.12 1.07 0.91 0.80 0.73 0.67
500 1.18 1.12 1.07 0.91 0.80 0.73 0.67
630 1.18 1.12 1.07 0.91 0.80 0.73 0.67
Multi core              
50 1.13 1.09 1.06 0.92 0.83 0.76 0.71
70 1.14 1.09 1.06 0.92 0.83 0.75 0.70
95 1.14 1.09 1.06 0.92 0.83 0.75 0.70
120 1.14 1.10 1.06 0.92 0.82 0.75 0.69
150 1.14 1.10 1.06 0.92 0.82 0.75 0.69
185 1.14 1.10 1.06 0.92 0.82 0.74 0.69
240 1.15 1.10 1.07 0.92 0.81 0.74 0.69
300 1.15 1.10 1.07 0.92 0.81 0.74 0.69
400 1.15 1.10 1.07 0.92 0.81 0.74 0.69